Silicone sized paper and cellulosic fiber



United States Patent Ofi ice 3,438,807 Patented Apr. 15, 1969 SILICONE SIZED PAPER AND CELLULOSIC FIBER Joseph E. Pikula, Depew, N .Y., assignor to Union Carbide Corporation, a corporation of New York No Drawing. Filed Dec. 15, 1965, Ser. No. 514,125

Int. Cl. Dllh 3/10, 3/62, 1/40 U.S. Cl. 117-154 5 Claims ABSTRACT OF THE DISCLOSURE Sized cellulosic fiber and paper characterized by the presence on at least a surface portion thereof of an addition product of a hydrosilicon compound containing at least one silanic hydrogen bond with a fatty acid ester containing at least one unsaturated carbon-to-carbon bond; the addition product containing from about 0.2 to about 85 weight percent silicon and being present on the fiber in an amount at least sufficient to enhance the resistance of the fiber to wetting by an aqueous medium.

This invention relates to paper making. In one aspect this invention is directed to a method for sizing paper and the article of manufacture derived therefrom.

Cellulosic fibers constitute the bulk of finished paper. In addition thereto, however, a wide variety of internally contained or surface carried ingredients are employed to impart particular desired properties to the paper. These ingredients include fillers such as clay, chalk, and other oxides or salts of metals, dyes and colorant materials, mordants, retention aids, wet strength agents, sizing agents, and the like.

Paper is sized in order to increase its resistance to penetration by liquids, particularly water. The most common sizing system is rosin soap (sodium rosinate) and papermakers alum (aluminum sulfate). In addition to these, hydrocarbon and natural waxes, starch, sodium silicate, glues, casein, synthetic resins, latices, etc. have been employed as sizing agents.

As with almost all paperrnaking operations, sizing still retains much of the empiricism and art of earlier times. The techniques of sizing are many and varied, and they depend upon such variables as pH, temperature, other chemicals present, fiber type and condition. The exact mechanism of sizing also varies with the particular sizing agent employed, and in most instances is still the subject of controversy. For example, when rosin and papermakers alum are used, it is still a generally accepted but unproven theory that sizing is achieved by virtue of a colloidal system in which the negatively charged fibers hold a layer of positively charged aluminum hydroxide particles which, in turn, hold the negatively charged rosin. Such a theory is not necessarily valid with respect to other sizing agents such as glue or a natural wax.

In addition to the variety of mechanisms apparently involved with difierent sizing agents, it is not possible to predict as a rule the sizing effect any particular agent will have on one material from knowledge of the same sizing agent on a different material or substrate.

Silicones containing relatively large amounts of methylhydrogen siloxane heretofore have been reported as sizing agents for paper. Such materials suffer from three major shortcomings, however: (a) considerable time is required to develop lasting water resistance under conventional paper treating conditions, (b) the useful life of the silicone is shortened to impractical time periods when the silicone is used in conjunction with catalysts which shorten the necessary cure time, and (c) the presence of even small amounts of alum in the paper retards still further the development of water resistance.

-It is the principal object of this invention to obviate the aforesaid difiiculties while at the same time providing excellent silicon-containing sizing agents.

It is another object to provide a high quality sized paper.

It is a still further object to provide a method for sizing cellulosic fibers.

These and other objects will become readily apparent to the skilled artisan upon reference to the ensuing specification and claims.

The objects of this invention are achieved by sized cellulosic fibers, such as paper, characterized by the presence on at least the surface portion thereof of an addition product of a hydrosilicon compound with a fatty acid ester containing at least one unsaturated carbon-to-carbon bond. The addition product contains from about 0.2 to about weight percent silicon and preferably from about 1 to about 50 weight percent silicon, and is present on the cellulosic substrate in an amount at least sufficient to enhance the resistance of the cellulosic substrate to wetting by an aqueous medium.

The amount of the addition product present in or on the final paper product, depends on the intended end use of the paper product. As soon as some increase in resistance to wetting is discernible, as compared to the untreated state, the paper can be deemed sized. The degree of sizing can be carried on until a continuous layer of the sizing agent, i.e., the addition product, is deposited on the surface of the paper. In the latter case the porosity of the sized paper is considerably reduced. Also, when the paper is sized to a relatively high degree, i.e., hard sized, the paper will exhibit release properties for some adhesives. However, even in the case of hard size the thickness of the addition product layer on the surface of the sized paper does not exceed about one-half mil. Thicker layers can be produced of course; however, no additional commensurate benefits can be gained thereby.

The method of this invention can be practiced either before, during, or after the paper forming operation. The hydrosilicone-fatty acid ester addition product can be contacted with or applied to the paper fibers by itself, as a solution in a compatible solvent, or as an emulsion.

If the addition product is applied as a solution, typical solvents are the aliphatic or aromatic solvents such as hexane, mineral spirits, kerosene, toluene, xylene, and the like. Also compatible are the halogenated solvents such as perchloroethylene and the like.

If the addition product is contacted with the paper fibers as an emulsion, which in many cases may be very desirable, any of the conventional anionic, cationic, nonionic emulsifiers, or compatible mixtures thereof may be utilized. The amount and the exact type of emulsifier is generally determined by practical considerations with respect to the application procedure followed, emulsion stability, and minimum interference to the hydrophobing properties of the addition product. For emulsification the non-ionic emulsifiers such as polyvinyl alcohol, trimethylnonylpolyethylene glycol/nonyl phenyl polyoxyethylene glycol ether blends, polyoxyethylene sorbitan monooleate, and the like, are preferred. Excellent emulsions exhibiting very good sizing properties have been obtained by premixing the non-ionic emulsifier, Water, and the hydrosilicon-fatty acid ester addition compound in a suitable container and then passing the resulting admixture through a homogenizer at a relatively high (about 4500 p.s.i.) pressure.

The addition of the sizing agent to the paper fibers prior to the time when they are interfelted into a relatively low water content, self-supporting sheet is conventionally re ferred to as wet end sizing. Similarly, when the sizing agent is applied to the already formed paper, the process is conventionally termed dry end sizing.

When, according to this invention, the sizing agent is applied to the wet end of the papermaking process it can be applied in a Water dispersible form such as an aqueous emulsion, for example. As such it. can be added to the water dispersed pulp at any time up until the fibers are picked up on the wire or cylinder of the paper machine. Preferably the addition is carried out after the heating operation which produces fibers from the starting material.

The optimum procedure for applying the sizing agent according to this invention at the dry end of the papermaking process depends on such factors as the type of papermaking equipment available, weight and speed of the paper, the desired degree of sizing, etc. Any conventional technique of application, such as a water box on a calender, tub sizing, size press, transfer roll, spraying, and the like, can be employed.

The hydrosilicon compounds that are suitable for use in the present invention must contain at least one silanic hydrogen bond. Such compounds include both hydrosilanes and hydrosiloxanes; they may be monomeric or polymeric; linear, branched or cyclic in structure; and may contain from one silicon bonded hydrogen atom to any greater number of silicon bonded hydrogen atoms per molecule. In addition, any one silicon atom may contain from 1 to 4 hydrogen atoms bonded directly to it. The remaining valence bonds of the silicon atom, that is, those not bonded either to hydrogen or oxygen atoms, may be satisfied with substituted or unsubstituted, saturated or olefinically unsaturated, aliphatic or aromatic hydrocarbons, or with functional groups; preferably such functional groups are free of active hydrogen atoms. Groups containing no active hydrogen atoms include ethers, esters, halogens, nitriles and dialkyl amides. These functional groups may be bonded either directly to the silicon atom or be substituted on the above-mentioned hydrocarbon groups. Saturated hydrocarbons are preferred.

The hydrosilanes that are useful for the preparation of the addition products used in the present invention are represented by the formula where R is selected from the group consisting of (a) an unsubstituted hydrocarbon group, (b) a functionally substituted hydrocarbon group wherein the functional group is a non-active hydrogen atom containing functional group, (c) non-active hydrogen atom containing functional group, and (d) a halogen; and where x represents any whole number from to 3 inclusive. The hydrocarbon groups (substituted or unsubstituted) may be saturated or olefinically unsaturated and either aliphatic, aromatic or mixtures thereof. Non-active hydrogen atom containing functional groups include: ethers, esters, acetals, aromatically bonded halogens, tertiary amines, dialkyl amides, and nitriles.

The hydrosiloxanes that are useful include those siloxanes that are composed essentially of groups having the repeating formula:

Rb HBSIL Where R is the same as defined above, a has a value of 1 to 3 inclusive, b has a value of 0 to 2 inclusive, and (a-l-b) has a value of 1 to 3 inclusive, all numbers being whole numbers.

Siloxanes that are useful for the preparation of the addition products also include copolymers of units represented by Formula B above with units represented by Formula C below wherein the ratio of (B):(C) may be 4 from 60:1 to 111000 and preferably from 60:1 to 1:60. Formula C may be represented as: (c) RuSiO where R is defined as above and c has a value of 0 to 3 inclusive.

Illustrative of unsubstituted saturated aliphatic hydrocarbons of alkyl groups represented by R in Formulae A, B and C above are methyl, ethyl, propyl, butyl, octadecyl, cyclohexyl and cyclopentyl groups. Illustrative of unsaturated, aliphatic hydrocarbons or alkenyl groups are vinyl butenyl, cyclopentenyl and cyclohexenyl. Illustrative of saturated aryl groups are phenyl or naphthyl groups, illustrative of alkaryl groups are tolyl and xylyl; illustrative of aralkyl groups are benzyl and beta-phenylethyl. Illustrative of functionally substituted hydrocarbon groups which may be bonded to silicon atoms are dimethylaminoethyl, methoxymethyl and carbethoxy.

Preferred copolymers composed of units represented by Formulae B and C above may be represented by the formula:

where R represents any monovalent hydrocarbon group, for example, methyl, ethyl, propyl, cyclohexyl, phenyl, vinyl, tolyl or benzyl. Where more than one R group is attached to any particular silicon atom they may be the same or different groups. Preferably R is a saturated hydrocarbon group; the methyl group being the most preferred. The value of x may have any average value of from 0 to about 10 and y may have any average value of from 1 to about 10 For example, if in Formula D x=0, y=l, and all R's are methyl, the siloxane, hereafter labeled siloxane (I) is:

(CHa)aSi0S|iOSi(CH CH3 If in Formula D x=2l.5, y=3.5 and all Rs are methyl, the siloxane, hereafter labeled siloxane (II) is:

r (OH3)3SiO SIiO s|l0 Sl(CH3)3 If in Formula D x=9, y=3.5 and all Rs are methyl, the siloxane, hereafter labeled siloxane (III) is:

i (CH S1O S10 (S Si(CHs)3 If in Formula D x=0, y=40 and all the Rs are methyl, the siloxane, hereafter labeled siloxane IV is:

Sill-I (OCH The fatty acid esters containing at least one unsaturated carbon-to-carbon bond contemplated by the present invention can be monoesters or polyesters. Particularly con i (CH3)aSiO SIiO templated are oils which are mixtures of various triglycerides of fatty acids in which at least one unsaturated ester is present. Preferably carbon-to-carbon double bonds prevail. Oils within the foregoing characterization are ordinarily categorized into three groups: nondrying, semi-drying, and drying oils. For the purposes of the present invention preferred are the semi-drying and drying oils.

Illustrative non-drying oils include olive, castor, and rapeseed oils. Semi-drying oils include cottonseed, soybean, sunflower, safilower, and walnut oil. Drying oils include linseed, perilla, dehydrated castor, oiticia, and tung oils.

It should be noted, however, that not only vegetable oils but also animal fats and fish oils containing unsaturation, for example, tallow, cod liver oil, etc. may be employed. Moreover, the oils need not be natural oils or glycerol esters in order for them to be suitable for the purposes of the present invention. They may be esters of any monohydric or polyhydric alcohol, for example, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, pentaerythritol, sorhitol, mixtures of the foregoing, and the like.

As a catalyst for the hydrosilicon compound addition to a fatty acid ester containing at least one unsaturated carbon-to-carbon bond any metallic compound may be used which promotes the addition of a hydrosilicon compound to an olefinically unsaturated compound. Such catalysts are well known in the art. In general, these catalysts include the stable Group VIII metals and their salts. These metals are platinum, ruthenium, rhodium, iridium, palladium, osmium, cobalt, nickel and iron. Platinum is the preferred metal. It may be used in various forms such as platinum on carbon, platinum on alumina, platinum black, platinic chloride, potassium chloroplatimate and the most preferred form, chloroplatinic acid.

Illustrative of the above salts which can be employed as catalysts are palladous acetate, formate and propionate, the alkali metal halo salts, e.g., potassium chloropalladate, sodium chloropalladate or platinate and the like.

The iron, nickel and cobalt salts are less active than the other Group VIII metals, consequently, those salts which are soluble in the reaction medium so as to provide a homogeneous reaction solution are preferred. Illustrative of these salts are the octoates, abietates, naphthenates, and linoleates.

In addition, the halides and oxides of platinum, ruthenium, iridium, rhodium, palladium and osmium are useful catalysts. Illstrative of such compounds are bromoplatinic acid, magnesim chloropalladate, trimethylplatinum iodide, trimethylplatinum chloride, palladous dichloride, rhodium chloride, ruthenium trichloride, palladous oxide, osmium monoxide, platinous monoxide and the like.

Still other useful catalysts are organic complexes of the above metals such as carbonyl complexes of the metal salts, and olefin or acetylene complexes of said metals. Exemplary are the complexes of platinum or palladium with ligans, one or more of which can be or have been displaced by an alkene, e.g. ethylene, propylene, butylene etc. to form a platinum-olefin complex or a palladium-olefin complex. For example, palladous acetylacetonate, palladous dibenzonitrile dichloride, ethylene platinous chloride, bis(cyclopentadienyl) osmium, cyclopentadienyl iridium, cyclopentadiene, cobalt pentacarbonyl and its hydride, iron carbonyls, nickel carbonyls and hydrides, ferrocenes, nickelocenes, cobaltocenes etc.

The above catalyst may be employed in a concentration of about 0.1 to 5000 p.p.m. calculated as elemental metal based on the weight of the polyene; the preferred range being 0.1 to ppm. To facilitate handling of the relatively small amounts of catalysts required, it is convenient to employ a solution of the catalyst in an organic solvent. Useful solvents include ethylene glycol di(lower alkyl) ethers, polyethylene glycol di(lower alkyl) ethers, such as the methyl and ethyl ethers; isopropanol, dioxane and tetrahydrofurane.

It is preferable that the metal catalyst be soluble in at least one of the reactants or in an organic solvent which is miscible with one of the reactants, so that the reaction may be carried out in a homogeneous system. However, the invention is not restricted to homogeneous systems or to such soluble catalysts. When catalysts which are insoluble are used, such as platinum dioxide, the concentration of the catalyst will ordinarily have to be 10 to times greater than when a soluble catalyst is used. For example, when H PtCl -6H O in dimethoxy ethane or dioxane is used as the catalyst 0.1 to 10 ppm. platinum based on oil is sufficient, whereas 500 to 5000 p.p.m. of platinum is required when insoluble PtO is used. Still greater amounts of catalyst are needed when nickel or cobalt compounds are used instead of platinum.

Reaction conditions may be varied. Although the preferred reaction temperature for the addition reaction is from about 100 to about 200 C., the operable range is from about 0 C. to about 300 C. The addition reaction does not require pressure unless volatile solvents or reactants are used.

The addition reaction may be carried out with or without the presence of solvents. Useful solvents include ethylene glycol or polyethylene glycol, dimethyl or diethyl ether, tetralin, dioxane, dioxolane, tetrahydrofurane, benzene and xylene.

Since the drying of the so-called paint oils (i.e., linseed, tung, and soybean) can be promoted by the addition of driers, such driers can also be employed with the addition products employed for paper sizing in accordance with this invention. The driers usually are catalytically active metals existing in at least two valency states, e.g. Pb, Co, Mn, and the like, and are used in the form of oil soluble organic salts such as the octoates, the naphthenates, and the like.

Any kind of fibrous cellulosic material such as wood or cotton can be subjected to the present sizing treatment. The paper can be made using any type of wood, pulping procedure, bleaching procedure, etc. The paper can also contain fillers such as clay, titanium dioxide, calcium carbonate, and the like, and can also contain the conventional paper makers additives such as starch, rosin, and wet strength resins. Typical types of paper that can be sized in accordance with the present invention are made from 1) reclaimed ground wood, (2) unbleached soft woodkraft, (3) bleached soft wood and mixed hardwood; the soft woods having been prepared by the sulfate, sulfite, or soda process, (4) highly hydrated pulps supercalendered to a smooth, dense paper, and the like.

Sizing is complete as soon as the paper treated with the hydrosilicone-fatty acid ester in accordance with this invention has dried. It is usually not necessary to subject the treated paper to elevated temperatures to effect a cure. Of course, elevated temperatures can be employed during drying Without any adverse effect provided the degradation temperatures of the paper or the addition product are not exceeded.

As pointed out before, sizing of the paper is effective as soon as a sufficient amount of the addition product is deposited on the fibers to enhance the Wetting resistance of the paper as compared to that of an untreated sample of the same paper. Generally, relatively small amounts of the addition product are necessary to attain this end. For example, a satisfactory size of paper used for the manu facture of gypsum board was obtained with about 0.8 lb. of the addition product of MD D M (identified in Table I below) with tung oil per one ton of 72 lb./ 1000 ft. paper.

It has further been found that particularly good sizing of paper finding its use in the manufacture of gypsum board can be achieved by an addition product where the hydrosilicon compound is present in an amount in the range from about 10 to about 40 weight percent of the addition product and can be represented by the average formula paper. Thereafter the glassine paper was dried for about 40 seconds in an oven at about 160 C.

The dried glassine paper exhibited excellent release or abhesive properties relative to an adhesive tape which failed to adhere to the paper after being applied thereto. However, the adhesive tape did adhere to other surfaces after being contacted with the treated glassine paper.

Example IV An aqueous emulsion was prepared from addition prod- TABLE I.CHARACTERIZATION OF ADDITION PRODUCTS Analysis Percent N0. Oil type Silicon type silicone in Residual SiH, Percent product cc. H/g. prod. silicon in product Example I Addition product No. 1 (about grams) was admixed with a drier (mixture of octoate soaps of lead, cobalt and manganese in an amount sufiicient to provide about 0.15 weight percent Pb, about 0.015 weight percent Co, and about 0.0075 weight percent Mn in the resulting admixture, based on the weight of addition product No. 1 present) and mineral spirits. The resulting solution "was then diluted with mineral spirits to a concentration of about 0.1 weight percent addition product No. l. A piece of rosin-sized, 90 lb. kraft paper was dipped into the solution. Thereafter the piece of paper was removed from the solution and dried in air.

A drop of water placed on this piece of paper after it was dry exhibited a good contact angle. When this paper was tilted at an angle the drop of water rolled ed.

A drop of water when placed on an identical piece of paper but for the contacting with addition product No. 1 was partially absorbed by the paper and would not roll 01f when the paper was tilted.

Example II Addition product No. 1 (about 30 grams) was admixed with a drier (mixture of octoate soaps of lead, cobalt and manganese in an amount suflicient to provide about 0.15 weight percent P-b, about 0.015 weight percent Co, and about 0.0075 weight percent Mn in the resulting admixture, based on the weight of addition product No. l present) and mineral spirits. The resulting solution was diluted with mineral spirits to a concentration of about 2 weight percent of addition product No. 1.

A piece of cotton print cloth, 80 by 80 ends per inch was immersed in the foregoing preparation, removed therefrom, squeezed by hand to remove the excess, and then stretched on a rack and permitted to dry. After air drying at room temperature the resulting sized cellulosic fiber was subjected to a spray test (AATCC spray test). The sized cloth had a spray rating of 80 as compared to the same cloth untreated, the spray rating of which was 0.

Example III Addition product No. 2 (about 15 grams) was dissolved in toluene (about grams). The drier used was a mixture of octoate soaps in an amount to give a concentration of about 0.3 weight percent Pb, about 0.03 weight percent Co, and about 0.015 weight percent Mn, based on the weight of addition product No. 2. Thereafter the resulting solution was heated to about 100 C. on a hot plate and then cooled to about room temperature.

About 3.34 grams of the resulting solution were diluted with about 21.66 grams of hexene. The diluted solution was then applied to glassine paper with a No. 8 R.D.S. rod so as to obtain a thin coating equivalent to about 0.4 lb. of addition product No. 2 per about 3000 square feet of uct No. 1 using polyoxyethylene sorbitan monooleate as the emulsifier. The emulsion was then further diluted with water to an addition product No. 1 concentration of about 1.6 weight percent.

The resulting emulsion was then applied to gypsum board paper (made from a stock containing repulped newsprint and repulped kraft paper) by passing the paper between two rolls on one of which the emulsion was distributed by means of a water box. The loading on the paper was about one pound of addition product No. 1 per one ton of paper.

The paper treated in the above manner was then conditionecl at about 20 C./50% relative humidity, and water absorption tests (TAPPI T-441) were made after aging for about 5 days. The water used was at about 50 C. and the contact time was about 3 minutes. The Cobb water absorption values, expressed in grams/ cm. after the 3 minute contact time were less than about 0.7. Gypsum board paper not treated with addition product No. 1 exhibited Cobb water absorption values in the range from about 1.5 to 2.0.

Example V The gypsum board paper treated in accordance with the method of Example IV was tested for its ability to make gypsum board. Twelve inch square envelopes, sealed on three sides and open on the fourth, were made of the paper. The treated surface was situated on the inside. The envelopes were then placed in a metal mold measuring 12 inches by 12 inches on the side and /2 inch thick. The mold was open at the top.

Wet, uncured gypsum, formulated in a commercial core mix and containing about one-half the normal amount of starch was poured into the envelope contained in the mold. The reduced starch content results in a more severe test of the suitability of the gypsum board paper. The filled envelope was then permitted to cure in the mold. After the gypsum had set, the thus produced gypsum board was removed from the mold and dried in a forced air oven to a surface moisture content of about 10 percent or less.

An examination revealed that the dried gypsum board was of good quality and that the bond of gypsum to the treated paper was strong. A gypsum board prepared in a like manner but with untreated paper exhibited a weak bond between the gypsum and the paper.

Example VI To an emulsion prepared in accordance with Example IV was added a dried (octoate soaps in an amount to give 0.15 weight percent Pb, about 0.015 weight percent Co, and about 0.0075 Weight percent Mn). Gypsum board paper treated in a manner similar to that of Example 1V exhibited Cobb water absorption values of less than about 0.7 after aging for about 5 to 7 days.

When a gypsum board was prepared in accordance with the procedures of Example V a good bond between the treated paper and the gypsum was obtained.

Example VII Example VI was repeated using addition product No. 3. The treated gypsum board paper exhibited Cobb water absorption values of less than about 0.7 after aging for about 9 to 12 days. A good bond was obtained between the treated paper and the gypsum.

Example VIII Example VI was repeated using addition product No. 4. The treated gypsum board paper exhibited Cobb water absorption values of less than about 0.7 after aging for about 6 to 8 days. A good bond was obtained between the treated paper and the gypsum.

Example 1X An aqueous emulsion was prepared of addition product No. using a mixture of trimethylnonylpolyethylene glycol and nonylphenylpolyethylene glycol as an emulsifier. The emulsion was then diluted with water to a concentration such that the loading produced on bleached soft wood and mixed hardwood paper would be about 3 pounds of addition product No. 5 per one ton of the paper when calender applied. The paper was then treated with the above emulsion and dried for about 3 minutes at about 88 C.

A Cobb water absorption value using room temperature water and a contact time of about 1 minute of about 0.17 was obtained after the treated paper was aged for about 24 hours. Untreated paper subjected to the same test gave a value of about 1.0.

Example X The procedure set forth in Example IX was carried out using additional product No. 6. The treated paper had a Cobb water absorption value of about 0.28 immediately after drying in the drum drier.

Example XI In a manner otherwise similar to Example II, after being hand-squeezed to remove the excess of the sizing agent, a piece of cotton cloth was dried in an oven for about 5 minutes at about 110 C. After the dried cloth had cooled to room temperature it was subjected to a spray test (AATCC spray test). Again a spray rating of 80 was obtained.

Thereafter the cloth was washed twice in a home automatic washer using an anionic household detergent and water at about 71 C. The cloth was air-dried overnight and then subjected to another spray test in the same manner as above. A spray rating of 70 was obtained.

In contradistinction thereto, a cotton cloth treated with a commercial silicone of the type (CH HSiO) while initially exhibiting a spray rating of 100, after two washings as above exhibited a spray rating of 0.

From the foregoing it is readily apparent that the sizing method of the present invention imparts a wetting resistant surface to cellulosic fibers that is more durable.

Example XII An aqueous emulsion of addition product No. 1 was prepared using a mixture of trimethylnonylpolyethylene glycol and nonylphenylpolyethylene glycol as an emulsifier. The emulsion was then diluted with additional water and combined with a starch solution. The concentration of the various ingredients in the resulting solution was adjusted so as to give a loading of about 1 lb. of addition product No. 1 and about 40 lbs. of starch per ton of paper (bleached soft wood and mixed hardwood) in a calendering operation.

Paper made from bleached soft wood and mixed hardwood was treated with the above emulsion so as to obtain the aforementioned loadings and thereafter dried in a drum drier for about 3 minutes at about 88 C.

The resulting treated paper exhibited a Cobb water absorption value of about 0.21 after aging for about 2 hours at about room temperature. Untreated paper under the same test conditions exhibited a Cobb water absorption value of about 0.85.

The foregoing discussion and the examples are to be taken as illustrative. Still other variations within the spirit and scope of this invention will readily present themselves to one skilled in the art.

I claim:

1. Sized cellulosic fiber characterized by the presence on at least a surface portion thereof of an addition product of a hydrosilicon compound containing at least one silanic hydrogen bond with a fatty acid ester containing at least one unsa-turated carbon-to-carbon bond; the addition product containing from about 0.2 to about weight percent silicon and being present on the fiber in an amount at least sufiicient to enhance the resistance of the fiber to wetting by an aqueous medium.

2. Sized paper characterized by the presence on at least a surface portion thereof of an addition product of a hydrosilicon compound containing at least one silanic hydrogen bond with a fatty acid ester containing at least one unsaturated carbon-to-carbon bond; the addition product containing from about 0.2 to about 85 weight percent silicon and being present on the paper in an amount at least sufficient to enhance the resistance of the paper to Wetting by an aqueous medium.

3. Sized paper in accordance with claim 2 wherein the addition product contains from about 1 to about 50 weight percent silicon.

4. Sized paper in accordance with claim 2 wherein at least a surface portion of the paper contains an addition product of a hydrosilicon compound represented by the formula R' SiO(R' SiO) (RHSiO) SiR' where R is a monovalent hydrocarbon group, 2: has a value of from 0 to about 10 and y has a value of from about 1 to about 10 with a drying oil.

5. Sized paper in accordance with claim 2 wherein at least a surface portion of the paper contains an addition product of a hydrosilicon compound represented by the formula R' SiO(R' SiO) (RHSiO) SiR where R' is a monovalent hydrocarbon group, J: has a value of from 0 to about 10 and y has a value of from about 1 to about 10 with a semi-drying oil.

References Cited UNITED STATES PATENTS 1,706,840 3/ 1929 Clapp 162-179 2,507,200 5/1950 Elliott et a1. 162-164 X 2,535,239 12/1950 Sowa 260-398 2,544,342 3/1951 Miller et a1. a 260-398 2,646,373 7/1953 MacMullen et a1. 162-158 X 3,046,160 7/1962 Dengler 162-164X FOREIGN PATENTS 689,604 4/1953 Great Britain.

529,283 8/1956 Canada.

908,988 10/1962 Great Britain.

WILLIAM D. MARTIN, Primary Examiner.

M. LUSIGNAN, Assistant Examiner.

U.S. Cl. X.R. 

